(1) Field of the Invention
This invention relates to a polyether-ester amide and a transparent thermoplastic resin having a permanently antistatic property
(2) Description of the Related Art
A polyether-ester amide synthesized from an amide-forming component, a poly(alkylene oxide) glycol component and a dicarboxylic acid component is widely used industrially as a thermoplastic elastic molding material. This polyether-ester amide is disclosed, for example, in U.S. Pat. No. 3,044,987 and U.S. Pat. No. 3,455,734. This polyether-ester amide is crystal-line and is not a polymer having a good transparency.
Polycarbonates and polymethacrylates are known as transparent resins. However, the technique of destaticizing polycarbonates has not been established. The technique of destaticizing polymethacrylates is known but is not widely used because the treatment is very expensive.
A resin comprising a rubbery polymer and a matrix resin, in which the refractive indexes of rubbery polymer and matrix resin substantially agree, for example, a methyl methacrylate/butadiene/styrene copolymer (MBS resin) or a methyl methacrylate/acrylonitrile/butadiene/styrene copolymer (MABS resin), is widely used in various fields as a resin having an excellent impact resistance and transparency. Resins of this type have excellent mechanical strengths and optical characteristics but they have a poor antistatic property. Therefore, utilization of these resins for IC carrier cases and OA device covers in which prevention of static is desired, and for various dust-proof articles and parts is difficult.
As a process for destaticizing a transparent resin, a process is known in which a hydrophilic rubbery polymer formed by copolymerizing a conjugated diene and/or an alkyl ester of acrylic acid with a vinyl monomer having an alkylene oxide group is graft-polymerized with a vinyl monomer, the graft chain having substantially the same refractive index as that of the polymer (see, for example, Japanese Unexamined Patent Publication No. 55-36,237). Although a practical antistatic effect can be attained according to this process, the process still has a problem in that since a special hydrophilic rubbery polymer is used, preparation is complicated, and the obtained resin has poor mechanical characteristics such as impact resistance and elastic modulus.